Boiler furnace



Sept. 12, 1933.

J. c. HOBBS 1,926,773

V BOILER FURNACE Original Filgd Aug. 1. 1925 3 Sheets-Sheet 1 INVENTOR I M ATTORNEYS Sept. 12, 1933.

J. HOBBS 1,926,773

BOILER FURNACE Original Filed Aug. 1. 1925 3 Sheets-Sheet 3 l/VVENTOR 7 C W 1:!

.4 TTOANE Vs Patented Sept. 12, 1933.

BOILER FURNACE James G. Hobbs, Painesville, Ohio Application August 1, 1925, Serial No. 4%,424 Renewed May 7, 1931 14 Claims. (01. 122-435) My present invention relates to furnaces, parfuel is burned, and more particularly when such furnaces are used in connection with steam boilers. My invention will be best understood from the following description and the annexed drawings, in which Fig. 1 is an illustrative embodiment of my invention in a steam boiler furnace; Fig. 2 is a partial section on the line 2--2 of Fig. 1; Fig. 3 is an enlargement of a portion of Fig. 2, taken on lines 33 of Figs. 4 and 5; Fig. 4 is a section on the line 44 of Fig. 3; Fig. 5 is a section on the line 5-5 of Fig. 3, and Fig, 6 is a front view looking toward the right in Fig. 3, of a portion of the wall shown in Fig. 3.

Like reference charactersindicate like in the several views.

In the illustrative embodiment, the boiler has water tubes 10 connected to downtake headers 11 and uptake headers 12, these headers, in turn, being connected to an upper steam and water drum 13, all in the usual manner.

Beneath the boiler is a furnace in which the combustion chamber 14 has a gas outlet opening at its top, which, in this instance, is substantially as wide as the length of theboiler tubes, so that the lower tubes are exposed to the gases from the furnace for their entire length. The

parts furnace chamber has a short section of roof 15 through which projects one or more powdered fuel burners 16 through which the fuelis projected downward into the furnace chamber and ignited, the burning fuel taking the path indi cated by the arrows, all in the usual manner.

The furnace chamber has a front wall 17, a

' rear wall 18 and side walls 19 to form a combustion chamber which is substantially rectangular in horizontal section. While 'the front and side walls of this combustion chamber are vertical, it will be understood that each or all of them may be inclined to the vertical, if desired.

Extending across the lower part of the combustion chamber is a row of slag screen tubes 20, inclined to the horizontal and connected at their lower ends to a header 21 supplied by water from the drum 13 through a pipe or pipes 22. The upper ends of the tubes 20 are each connected to a tube 23 extending along the rear furnace wall 18, each tube. 20 being connected to a tube 23 by an angular fitting 24. The tubes 23 extend out through the rear furnace wall and lower end of the header 29 being fed with water from the drum 13 through the pipe 22. and the upper end of the header 28 being connected through a pipe 30 to the pipe 26.

As shown best in Figs. 2 to 6, the cooling tubes 27*are located in recesses 31 in the wall 19, preferably so that the tubes 27 are inside of the inner face of the wall 19. The wall 19 may be laid up in any desired manner, one form of the arrangement of the brick or tile in successive courses being shown in Figs. 4 and 5. Preferably the wall is provided with one or more courses of special tile 32, each engaged by a hook member 40 with one leg ofthe member entering a recess in tile 32 and the hook of the member extending over a flange of a fixed I-beam 33, against which the outer end of special tile 32 rests. The member 40 holds the wall in vertical position while, at the same time, permitting it to move in any direction in a vertical plane, the hook of the member 40 being free to move up and down in tile 32 and along the I-beam 33. This permits the wall freedom of movement to respond, not only to its own motions due to expansion and contraction, but also permits relative motion between tubes 27 and the fixed portions of the wall supports in spite of the fact that the tubes are partly buried in the wall 19. It will be understood that any other form of wall-holding device may be used instead of that illustrated.

The wall 19 is provided with the usual back ing plates 34, the space between these plates and the well being filled with a non-conducting material 35. r

Beginning at a point above the level of the tubes 20 and extending downward to a point below the level of such tubes is a recess 36 in the wall 19, the upper edge of this recess being stepped, as shown best in 1, so that, in general, it is parallel to the tubes 20. A plurality of small openings 37 are provided through the .walL 19 just below the upperpart of the recess 36. It will be noted inl ig. 2 that-the upper line of the recess 36 fornis a. sharp angle with the imier face of the wall 19.

tlilpurpose of the slag screen tubes 20 to chill the molten particles which fall downward out of the gases, so that when these particles strike the furnace bottom, they will not stick to each other to form a mass.

' In addition to these slag particles which fall to the furnace bottom-however, other slag particles are carried up with the gases and some of them will necessarily strike the side walls of the furnaces. It has been proposed to provide the side walls of such furnaces with cooling tubes by which the walls can be maintained at a temperature which will assist in maintaining the refractory walls. It has been proposed to place such tubes either against the inner face of the refractory walls or at a distance removed from such inner face. Both of these plans are objectionable, however, because the slag becomes chilled around the tubes and will build up into large masses on the walls. In operating the furnace of =my invention as illustrated in. the

drawings, I partially bury the cooling tubes in the furnace walls, so that the walls are cooled to keep them'below a destructive temperature and, at the same time, so that the cooling is not so great that the slag will accumulate to any considerable thickness over the walls. The furnace is operated in such a manner as to the rate of burning fuel therein, so that under normal conditions, a layer of cooled slag will deposit over the inner face of the walls and, of course, over the cooling tubes themselves This slag, however, acts as a kind of insulator, so far as the cooling tubes are concerned, so that, when the slag builds out to a very short distance, it. prevents the ready flow of heat from the furnace into the cooling tubes and as a consequence, the inner surface of this layer of slag is maintained in a more or less molten condition, so that the slag will flow down the face of the furnace wall.

If, now, the rate of combustion in the furnace is increased and the temperature of the walls thereby increased, the slag which has been chilled on the walls becomes sufficiently fluid to run of! leaving the cooling tubes 27 exposed to absorb more heat from the furnace chamber. In this manner, it is within the control of the operator to determine the layer of slag which will remain on the furnace wall for any given operating conditions, and, moreover, a kind of balance is established because obviously when the tubes are exposed by the melting of the layer of chilled slag, more heat will be absorbed from the furnace chamber, so that the 19'will be protected under all conditions.

The molten slag accumulating on the slag walls will, of course, flow down such walls, and unless some provision were made, would be chilled as the slag reaches the cooling zone formed by the tubes 20 and would thus accumulate at the lower part of the wall in a gradually increasing mass which would build out from the wall over the slag screen tubes 20. In order to. avoid this,'I provide a drip ledge high, enough above the cooling zone formed by the tubes 20, so that the slag at the drip ledge is always in a molten condition and will, therefore, drip freely from this ledge into'the cooling'zone. The recess 36 provides sucha drip ledge, which I have indicated at 36", and by cutting back the wall as at 36. I insure that the falling drops of slag will not strike the relatively cool side wall until the slag particles have chilled by passing through the-cooling zone..

It will be understood that the arrangement which I have shown is merely illustrative and that the embodiment of my invention may be'widely varied.- For instance, while I have shown the cooling zone at the bottom of the furnace chamber formed by the slag screen tubes 20, it will be obvious that it may be formed in any other suit- J1? able manner. It will also be understood that the cooling tubes 2'? and their connections to the. boiler or to any other source of cooling fluid may be widely varied.

It will also be understood that the wall cooling arrangement which I have shown can be applied to all or any of the furnace walls, as, for instance, to the rear wall 18 and that the term side walls as used herein refers to any of the vertical furnace walls and not merely the walls at the sides of the. boiler setting.

I claim:

1.A powdered fuel furnace having a combustion chamber with substantially vertical side walls, a row of slag screen tubes extending par allel to said side walls at the lower part of the combustion chamber, said side walls being provided with drip ledges at a higher level than the level of said row of tubes and arranged to permit molten slag to drip from said ledges clear from the portions of the wall below said ledges, said tubes, being inclined to the horizontal and said drip ledges being generally parallel to said tubes, and cooling tubes arranged to cool said walls adjacent said ledges.

2. A powdered fuel furnace having a combustion chamber with substantially vertical side walls, a row of slag screen tubes extending parallel to saidside walls at the lower part of the combustion chamber, said side walls having recesses in their inner faces extending from above to below the level of said tubes with the upper part of said recesses arranged to form drip ledges to permit molten slag to drip from said ledges, andcooling tubes arranged to cool said walls adjacent said ledges.

3. In a furnace, a stationary vertical wall formed of refractory material and having vertically extending spaced recesses in the inner face thereof, a cooling metallic tube in each of said recesses, the width of Qeach recess beinggreater than the diameter of the tube therein to provide a clearance space on either side of the tube, means to burn a slag-forming fuel in the furnace, and means independent of the tubes to hold the wall 120 in vertical position while. permitting it to move in any direction in a vertical plane.'

4. In a furnace, a stationary vertical wall formed of refractory material and having vertically extending spaced recesses in the inner face thereof, a cooling metallic'tube in each of said recesses, the width of each recess being greater than the diameter of the tube therein to provide a clearance space on either side of the tube, means to burn a slag-forming fuel in the furnace, and means independent of the tubes to hold the wall invertical position.

5. In a furnace, a vertically extending wall formed of refractory material and having vertically extending spaced recesses in the inner surface thereof, water tubes disposed in said recesses, with the inner surfacesof the tubes substantially flush with the inner surface of the adjacent refractory material, means for circulating water through said tubes, means for burning a slagforming fuel in the furnace, a fixed support for the refractory material adjacent said tubes and constructed and arranged to hold said material 'a'ga movement transversely to said inner surface of the wall, and means independent of said fixed support for supporting the tubes in said 6. In a furnace, a vertically extending wall formed of refractory material and having vertically extending spaced recesses in the inner surface thereof, water tubes disposed in said recesses, with the inner surfaces of the tubes substantially flush with the inner surface of the adjacent refractory material, means for circulating water through said tubes, means'for burning a slag-forming fuel in the furnace, a fixed support for the refractory material adjacent said tubes and constructed and arranged to hold said material against movement transversely to said inner surface of the wall, and means independent of said fixed support for supporting the tubes in said recesses, said support and. said supporting means being constructed and arranged so that expansion and contraction of the tubes and the refractory material may take place with respect to each other. I

7. In a furnace, a vertically extending wall formed of refractory material and having vertically extending spaced recesses in the inner sur-, face thereof, water tubes disposed in said recesses, with the inner surfaces of the tubes substantially flush with the inner surface of the adjacent refractory material, means for circulating water through said tubes, means for burning a slag-forming fuel in the furnace, a fixed support for the refractory material adjacent said tubes and constructed and arranged to hold said material against movement transversely to said inner surface of the wall, and means independent of said fixed support for supporting the'tubes in said recesses, said support and said supporting means being constructed and arranged so that expansion and contraction of the tubes and the refractory material may take place with respect to each other lengthwise of the tubes.

8. In a furnace, a vertically extending wall formed of refractory material and having vertically extending spaced recesses in the inner surface thereof, water tubes disposed in said recesses, with the inner surfaces of the tubes substantially flush with the inner surface of the'adjacent refractory material and with their ends extending outside the furnace, connections to said tube ends outside the furnace, means for circulating water through said tubes and connections, a fixed support for the refractory material adjacent said tubes and constructed and arranged to hold said material against movement transversely to said inner surface of the wall, and means independent of said fixed support for supporting the tubes in said recesses.

9. In a furnace, a vertically extending wall formed of refractory material and having vertically extending spaced recesses in the inner surface thereof, water tubes disposed in said recesses, with the inner surfaces of the tubes substantially flush with the irmer surface of the adjacent refractory material and with their ends extending outside the furnace, connections to said tube ends outside the furnace, means for.

circulating water through said tubes and connections, 9. fixed support for the refractory material adjacent said tubes and constructed and arranged to hold said material against movement transversely to said inner surface of the wall,

and means independent of said fixed support- ,for supporting. the tubes in said recesses, said support and said supporting means being constructed and arranged so that expansion and contraction of the tubes and the refractory material may take place with respect to each other.

10. In a furnace, a vertically extending wall formed of refractory material and having verticallyextending' spaced recesses in the inner surface thereof, water tubes disposed in said recesses and having ends bent outwardly through openings in the refractory material, said openings being of larger vertical dimension than the outside diameters of the tubes, the inner surfaces of the tubes being substantially flush with the inner surface of the adjacent refractory material, headers disposed outside the furnaceand connected to said tube ends, means for circulating water through said tubes, and means for independently supporting the tubes and the refractory material.

11. In a furnace, a vertically extending wall formed of refractory material and having vertically extending spaced recesses in the inner surface thereof, water tubes disposed in said recesses and having ends bent outwardly through openings in the refractory material, said openings being of larger vertical dimension than the outside diameters. of the tubes, the inner surfaces of the tubes being substantially flush with the inner surface of the adjacent refractory material, headers disposed outside the furnace and connected to said tube ends, means for circulating water through said tubes, means for independently supporting the tubes and the ref'ractory material, and means forming a slip joint between-portions of the refractory material to permit relative vertical movement therebetween.

12. In a furnace, a vertically extending wall formed of refractory material and having vertically extending spaced openings therein, water tubes disposedin said openings, with their ends extending outside the furnace, connections to said tube ends outside the furnace, means for circulating water through said tubes and connections, a fixed support for the refractory material adjacent said tubes and constructed and arranged to hold said material against movement transversely to said wall, and means independent of said fixed support for supporting the tubes in said openings. 13. In a furnace, a vertically extending wall formed of refractory material and having vertically extending spaced openings therein, water tubes disposed in said openings, with their ends extending outside the furnace, connections to said tube. ends outside the furnace, means for circulating water through said tubes and connections, a fixed support for the refractory ma- 7 terial adjacent said tubes and constructed and arranged to hold said material against movement transversely to said wall, and means independent of said fixed support for supporting the tubes in said openings,'said support and said supporting means being constructed and arranged so that expansion and contraction of the tubes and the refractory material-may take place with respect to. each other.

14. In a furnace, a vertically extending wall formed of refractory material and having vertically extending spaced openings therein, water tubes disposed in said openings and having ends bent outwardly through openings in the refrac tory material, said last-named openings being of larger vertical dimension than the outside diameters of the tubes, headers disposed outside the furnace and connected to said tube ends, means for circulating water through said tubes,. means for independently supporting the tubes and the refractory material, and means forming a slip joint between portions' of the refractory material to permit relative vertical movement 

